Evaluación de la actividad antimicrobiana in vitro de aceites esenciales frente a microorganismos patógenos y del deterioro de alimento

Abstract

Essential oils (EOs) are volatile compounds, rich in secondary metabolites such as monoterpenes and sesquiterpenes, noted for their antimicrobial activity, attributed to their hydrophobicity and high concentration of active phenols (thymol, carvacrol, and eugenol). These compounds alter the integrity of microbial membranes, increasing their permeability and generating oxidative stress. The agar diffusion method is used to categorize antimicrobial activity into four levels (+++; fully inhibited, ++; partially inhibited, +; slightly inhibited, and -; no inhibition). However, this method presented limitations due to the volatility and hydrophobicity of EOs, which affected their uniform diffusion. The in vitro evaluation of 50 EOs against 12 microorganisms revealed greater efficacy against Gram-positive bacteria due to their more permeable cell wall. Although Gram-negative bacteria are more resistant due to their complex outer membrane. EOs such as thyme and oregano were able to inhibit them thanks to their bioactive compounds. In contrast, anaerobic Clostridium perfringens showed complete resistance, likely due to their spore-forming capacity and the reduced production of reactive oxygen species (ROS) in the absence of oxygen, which limits the antimicrobial action of EOs. In fungi, thyme and cinnamon showed significant activity, while against beneficial bacteria the action was minimal. Their efficacy depends on the active compounds, oil volatility, and experimental conditions. Finally, EOs represent a sustainable and natural alternative as antimicrobial agents, aligning with the Sustainable Development Goals (SDGs). Their application in the food and pharmaceutical industries can improve food safety and meet the demand for natural preservatives in consumer products.